The present invention is directed to a device for moving items in a production operation, such as in a molding operation, where the device includes a mechanism for moving items to be produced or elements used in the production operation between working stations. The mechanism extends vertically and in addition to rotation about its vertical axis, can be moved upwardly and downwardly in carrying out the moving operations. In particular, the invention is directed to a molding operation for moving mold boxes from a conveyor device to a pattern device and, after the molding operation, moving a molded item from the pattern device to a conveyor.
Molding equipment including a mechanically driven intermittently rotatable turntable which supports at least two pattern devices is known from Swiss Pat. No. 318,528. In such equipment, mechanisms are arranged to be swung-in over the turntable and include controllable elements in operative connection with the turntable. Such mechanisms include elements for engaging mold boxes, for lifting and turning the boxes and, after the boxes have been used, for lifting and removing them.
Of necessity, in such molding equipment, heavy turntables are used which weigh in the range of 15 to 30 tons in the usual case. An extremely powerful rotary drive is required to effect the rapid rotation of the turntable and to effect the the precise positioning of the heavy masses being moved in the different working stations. As a result, a very great backlash is experienced in such equipment. In the molding operation there is the preliminary compression by vibrating or shaking and a final compression by a jolt squeezing operation. These steps are carried out at the same time that the molded parts are being lifted from the pattern device and, as a result, it is not possible without special measures to lift a molded part properly from the pattern device without damaging it. To improve the lifting process, additional brakes have been used which act both on the rotary movement of the turntable and on the elevating and turning mechanisms in the stationary position of the turntable. These brakes are provided to prevent rotary movement during the lifting of a molded part from the pattern device. However, up to the present time, it has not been possible to prevent mutual rotation of the turntable with the elevating and rotating mechanism during the lifting of a molded part from the pattern device to such an extend that a molded part can be lifted without any problems.
Moreover, it has not been possible up to the present to design the elevating and turning mechanism so that the elastic deformation of the lifting piston and the projecting arms which carry the clamps for engaging the molded parts, is kept within narrow limits so that they do not interfere with the lifting of the molded part from the pattern device.
Because of the disadvantages mentioned above, on one hand, the tightening of the patterns does not drop below a certain value and the sharp edges required for a molded part in many molding operations cannot be achieved.